Field of the Invention
The present invention relates to a wireless broadcast communication, and more particularly, to a method and apparatus for transmitting a pilot signal for a frequency-shared terrestrial broadcast system which operates in a single frequency network.
Discussion of the Related Art
The current terrestrial TV broadcasting generates a co-channel interference in a region covering about three times of the service radius, and thus it is not possible to use the same frequency in the region within the three times of the service radius. Likewise, the region where the same frequency cannot be used may be called a white space (WS), and the spectrum efficiency is very low due to the white space. Recently, as a way of improving the spectrum efficiency, transmission technologies for removing the white space and allowing an easy reuse of the frequency which enhances the transmission capacity and receiving strength are being developed.
As such, the literature “Cloud Transmission: A New Spectrum-Reuse Friendly Digital Terrestrial Broadcasting Transmission System”, which has been published through IEEE Transactions on Broadcasting, vol. 58, no. 3 in September, 2012, suggested a frequency-shared terrestrial broadcast technology which allows an easy reuse, does not generate a white space, and allows an easy establishment and operation of a single frequency network.
By using such a frequency-shared terrestrial broadcast technology, a broadcast company may transmit the same nationwide broadcast contents or regionally different broadcast contents through one broadcast channel. Recently, the literature “Robust synchronization for the OFDM-based cloud transmission system”, which has been published through IEEE International Symposium on Broadband Multimedia System and Broadcasting (BMSB), in June, 2013, suggested the frame structure of a frequency-shared terrestrial broadcast signal with the purpose of demodulation by distinguishing respective broadcast signals in a frequency-shared terrestrial broadcast system.
In the frequency-shared terrestrial broadcast, a receiver needs to be able to receive one or more frequency-shared broadcast signals in a region where signals transmitted from different transmitters overlap in a single frequency network, i.e., an overlapping region. That is, the receiver needs to be able to demodulate one or more frequency-shared terrestrial broadcast signals in a situation where the same channel interferences exist.